Y、Ca复合添加对AZ81镁合金组织和性能的影响  

Effect of Y and Ca Addition on Microstructure and Mechanica Properties of AZ81 Magnesium Alloy

作　　者：陈君[1,2] 张清 CHEN Jun;ZHANG Qing(School of Materials Science and Engineering,Henan University of Science and Technology,Luoyang 471023,Henan,China;Collaborative Innovation Center of Nonferrous Metals of Henan Province,Luoyang 471023,Henan,China)

机构地区：[1]河南科技大学材料科学与工程学院,河南洛阳471023 [2]有色金属共性技术河南省协同创新中心,河南洛阳471023

出　　处：《铸造》2018年第12期1099-1104,共6页Foundry

基　　金：国家自然科学基金项目(U1404501)

摘　　要：通过复合添加碱土元素Ca和稀土元素Y来改善AZ81镁合金的组织和力学性能,在CO_2+SF_6气体保护下制备了不同Ca、Y含量的AZ81-Y-Ca镁合金,通过光学金相显微镜(OM)、扫描电镜(SEM)、X射线衍射分析(XRD)、能谱分析(EDS)、拉伸及蠕变力学性能测试等手段研究了Ca、Y合金化对AZ81合金显微组织和力学性能的影响规律。结果表明,添加1.5%Y后AZ81合金的显微组织显著细化,Mg_(17)Al_(12)相的数量和尺寸减少,晶界和晶内形成块状和细小点状分布的Al_2Y相;AZ81-1.5Y合金中继续添加0.5%的Ca,其显微组织继续得到明显细化,组织中形成了点状或条状的Al_2Ca相。添加1.5%Y后AZ81合金的室温和高温拉伸力学性能得到大幅提高;随Ca含量的增加AZ81-1.5Y合金的抗拉强度呈先增大后减小的趋势,当Ca加入量为0.5%时得到最优的强化效果。Y和Ca的添加能够显著提高AZ81镁合金在175～200℃/70 MPa条件下的抗蠕变能力。在175℃/70 MPa条件下,Y和Ca的添加使得AZ81合金的蠕变应变量降低2～3倍,稳态蠕变速率降低近一个数量级。To improve the microstructure and mechanical properties of AZ81 magnesium alloy through the addition of Ca and Y minor elements,the AZ81-Y-Ca magnesium alloys were prepared by induction melting at the gas protection of CO2+SF6.The effects of Ca and Y addition on the microstructure and mechanical properties of AZ81 alloy were investigated by OM,SEM,XRD,EDS,tensile and creep tests.The results show that with the addition of 1.5%Y,the microstructure of AZ81 alloy is markedly refined,the size and amount of Mg17Al12phase are decreased,and the Al2Y phase can be found in the microstructure of the alloy.Further by the addition of 0.5%Ca,the microstructure of AZ81-1.5Y alloy is refined more distinctly,and the Al2Ca phase is formed.The tensile properties of AZ81 alloy at room temperature and high temperatures are significantly improved by the addition of 1.5%Y.The tensile strength of AZ81-1.5Y alloy increases firstly and then decreases with the increase of Ca addition,and the strengthening effect is best when the Ca addition is 0.5%.The creep properties of AZ81 alloy at175-200℃/70 MPa are significantly improved by the appropriate amount of Y and Ca compound addition.With the addition of Y and Ca,the creep deformation of AZ81 alloy at 175℃/70 MPa is decreased by 2-3 times and the steady-state creep rate is decreased by nearly an order of magnitude.

关 键 词：Y CA AZ81镁合金 蠕变性能 微观组织 

分 类 号：TG146.2[一般工业技术—材料科学与工程]